Telephone



(No Model.)

S. D. FIELD.

, SPEAKING TELEPHONE.

Patented Apr. 3

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UNITED STATES PATENT OFFICE.

STEPHEN D. FIELD, OF NEW YORK, N. Y.

SPEAKING-TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 275,178, dated. April 3, 1883.

Application filed April 16, 1881. (No model.)

To all whom it may concern:

Be .it known that I, STEPHEN D. FIELD, a citizen of the United States, residing in the city, county, and State of New York, have invented a new and useful Improvement in Speaking-Telephones, of which the following is a specification.

Myinvention relates to apparatus for receiving rhythmical impulses, waves, or vibrations which are sent through an electric circuit by means of any suitable transmitter adapted to that purpose, and for converting them into corresponding mechanical movements, whereby the atmosphere is thrown into vibration and musical or articulate sounds are produced. The same apparatus may also be utilized for the transmission of such musical or articulate sounds, the sonorous vibrations of the atmosphere being made to impinge upon a sensitive surface and throw the same into mechanical vibrations, which act upon a magneto-electric generator of suitable construction, and thus produce electric pulsations or undulations which traverse the line and produce the effects hereinbefore described at the receiving-station.

Transmitting and receiving telephones have heretofore been constructed by combining with an electro-magnet provided with a permanen tlymagnetic core a resilient plate of iron or other material capable of inductive action, which is of symmetrical form, and is rigidly supported at one or more of its edges, while the middle portion thereof, facing the pole or'poles of the magnet, is left free, so as to be capable of responding either to sonorous vibrations traversing the atmosphere or to electromagnetic pulsationsorundnIationstraversingthe helices surrounding the magnetic cores.

My invention consists in making use of a circular band or hoop of inductive metal, instead of the plate heretofore used, which band or hoop is supported at a single point, and passes through the field of the electromagnet at an opposite point in its circumference.

In the accompanying drawings, Figure 1 is a side elevation of my improved telephone, the inclosing-case being shown in section and Fig. 2 is a plan view ot'the same with the case removed.

In Fig. 1, A is a cylindrical bar of iron or steel, which has been rendered permanently through and fits tightly within the orifices a and a in the rim D.

Bis a coil or helix of insulated copper wire, enveloping one pole of the magnetic bar A. The terminals of the coil B are shown at b and b, and these are connected in a well-known manner with an electric circuit, which may include one or more additional telephones situated at other points. 0 is a circular endless band or hoop of metal capable of inductive action, preferably of thin rolled iron, having a uniform breadth equal to or somewhat exceeding the diameter of the magnetic bar A. This hoop is supported at one point only in its cir-' cumference, and is preferably firmly united to the extremity c of the magnetic bar A by means of a screw or rivet, or otherwise, as a more powerful action of the instrument is I thereby obtained. The band or hoop is mounted so as to be in close proximity to that pole of the magnetic bar A which is enveloped by the helix B, and consequently passes directly through its magnetic field.

The apparatus thus describedis preferably attached to and inclosed within a hollow annular case, D, which should be provided with a funnel-shaped mouth-piece, E, situated opposite that point in the circumference of the hoop which passes through the magnetic field of the bar A.

I have found that a cylindrical hoop which is of uniform breadth and is supported at a single point of its circumference, in the manner hereinbefore described, possesses the ca pacity of responding with equal facility to all rhythmical vibrations, whatever may be their pitch or intensity.

The operation of my improved apparatus is as follows: Assuming the helix B to be included in an electric circuit in the manner hereinbefore explained, a person desiring to transmit an oral communication places his mouth at or near the aperture 0 and speaks the message to be transmitted. The voice of the person speaking produces in the air sonorous vibrations or waves, which, as is well known,

purpose.

are of varying amplitude and succeed each other at varying intervals of time. The band or hoop 0, being rigidly supported at the point 0, but resilient and free to vibrate at all other points, including the portion within the magnetic field of the bar A, is thrown into vibrations which correspond, both in their amplitude and in their varying intervals, with the sonorous vibrations which impinge against it. The vibrations of the hoop 0 within the said magnetic field induce corresponding rhythmicalmagneto electric pulsations in the coil B, which are transmitted through the electric circuit and received upon a corresponding instrument, or any instrument suitable for the The reverse of this operation takes place when the instrument is employed for receiving oral communications from a transmitting-telephone at a distance. The electric pulsations received over the line traverse the coil B and give rise to varying magnetic intensities in the bar A, which in turn, by reason of the varying attractions exerted upon the hoop G, throw it into rhythmical vibrations, which are communicated to the air and thence to the ear of the listener, thus accurately reproducing the original sound uttered by the person at the sending-station.

I claim as my invention- 1. The combination,substantially as hereinbefore set forth, of a helix or coil enveloping an iron or steel bar, and a circular band or hoop of inductive metal, supported at a single point and traversing the magnetic field of said bar at an opposite point in its circumference.

2. The combination, substantially as hereinbet'ore set forth, of a helix or coil enveloping a polarized iron or steel bar, and a circular hand or hoop of inductive metal, which is in magnetic contact with one pole of said bar at one point of its circumference, and passes through the magnetic field of the opposite pole of said bar at an opposite point in its circumference.

In testimony whereof I have hereunto sub 5 STE PHEN DUDLEY FIELD.

Witnesses MILLER O. EARL, CHAS. A. TERRY. 

